DE102009015850B4 - An integrated engine cooling / clutch refilling system and method for use in a hybrid transmission - Google Patents

Abstract

A method of delivering fluid to a housing (13) of a hybrid transmission (12), the method comprising the steps of: raising a total system line pressure to cause fluid leakage or leakage of a control system (10); Passing the escaped fluid through at least one refill channel (24) to the housing (13); and directing the escaped fluid through at least one electric motor (A, B) within the housing (13) to cool the at least one electric motor (A, B); Collecting the fluid conducted via the at least one electric motor (A, B) to generate a back pressure in the housing (13).

Description

TECHNICAL AREA

The present invention relates to a system and method for cooling electric motors in a hybrid transmission.

BACKGROUND OF THE INVENTION

A hybrid transmission for a vehicle generally includes a plurality of clutches and a pair of electric motors for outputting mechanical power to a drive system of the vehicle. To work properly, the transmission usually requires a supply of pressurized fluid, such as conventional transmission oil. The pressurized fluid may be used for such functions as cooling and lubrication, and in some instances the operation of the torque transmitting devices. The lubrication and cooling capabilities of transmission oil systems affect the reliability and durability of the transmission. Additionally, multiple-speed transmissions require pressurized fluid for the controlled engagement and disengagement of the torque-transmitting mechanisms that serve to establish the ratios within the internal gear assembly.

With regard to exemplary hybrid transmissions, reference is made to the publications DE 601 06 376 T2 . DE 10 2005 011 890 A1 or DE 10 2005 034 930 A1 referenced, in which the cooling of the electric motors is done by existing in the transmission oil circuits.

Generally, pressurized fluid from a pump flows through valves and channels in a first electro-hydraulic circuit to the clutches to actuate the clutch. The fluid drains out of the transmission into a sump in the transmission where it is reused. The electric motors in the hybrid transmission can convert electrical power into mechanical power to operate the drive system. During operation of the transmission, the electric motors generate heat, requiring cooling of the electric motors. To cool the electric motors, a second electrohydraulic circuit is used to move fluid to cool the electric motors.

The invention is based on the object to provide a realization that allows efficient cooling of the electric motors of a hybrid transmission.

SUMMARY OF THE INVENTION

This object is achieved by a method having the features of claim 1 and a control system having the features of claim 11. Advantageous developments emerge from the dependent claims.

The method of claim 1 for supplying fluid to a housing of a hybrid transmission comprises raising a total system line pressure to cause leakage or escape of the fluid through a control system. The escaped fluid is passed through at least one refill channel to the housing. The escaped fluid is directed via at least one electric motor within the housing to cool the at least one electric motor. The fluid conducted via the at least one electric motor is collected to create a back pressure in the housing.

The control system of claim 11 for supplying a fluid to a hybrid transmission includes a trim valve configured to regulate the flow of fluid to the hybrid transmission. A supply line is operatively connected to the trim valve and configured to carry the fluid between the hybrid transmission and the trim valve. A refill channel is operatively connected to the trim valve and configured to deliver a leaked fluid from the trim valve to the hybrid transmission. A bypass passage operatively connects the supply line and the refill channel and is configured to supply additional fluid to the hybrid transmission.

A hybrid transmission includes a housing. In the housing at least one electric motor and at least one clutch are arranged. A control system is in fluid communication with the housing and includes at least one valve configured to regulate the flow of fluid to the housing. A supply line operatively connects the valve to the housing to transport the fluid between the housing and the valve. A refill channel operatively connects the valve to the housing to transport the fluid between the valve and the housing. A bypass passage operatively connects the supply line and the refill channel. The bypass passage is configured to supply additional fluid to the housing.

The engine cooling and the clutch refill are accomplished by using leakage fluid from the trim valves and the pilot valve. The leakage fluid is normally drained back to the transmission pan and wasted. By intercepting the leakage fluid and diverting it to motor windings of the electric motor, both the engine cooling and the clutch refill are efficiently accomplished. Without this configuration, a dedicated circle would have to be added to get the cooling of the electric motor, in which case valve leakage is lost to the transmission pan. Combining the circuits into one increases the overall system efficiency, which has an immediate positive effect on the fuel economy of the vehicle.

The advantages of the present invention will become readily apparent from the following detailed description of the best modes for carrying out the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Among the figures, which are exemplary embodiments, wherein like elements are numbered alike, is:

1 a schematic representation describing an electro-hydraulic control system, which is used together with a hybrid transmission;

2 a schematic partial view of the electro-hydraulic control system and the hybrid of 1 showing a flow path for supplying cooling flow to the electric motors within the hybrid transmission to cool the electric motors; and

3 a schematic partial view of the electro-hydraulic control system of 1 , which shows a flow path for refilling a clutch via a trim valve to extract air from the clutch.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

To refer to the drawings, wherein like reference numerals refer to like components, shows 1 an electro-hydraulic control system 10 together with a hybrid transmission 12 , The hybrid transmission 12 can be a case 13 with four clutches C1, C2, C3 and C4 and two electric motors A and B in the housing 13 are arranged to comprise.

The tax system 10 may include four trim valves T1, T2, T3 and T4 and two switching valves X and Y. The trim valves T1, T2, T3 and T4 and the two switching valves X and Y each have a valve housing 14 on, that several connections 16 Are defined. In the valve housing 14 is a valve element 18 slidably disposed between a stroked and an unstroked position. The valve housing 14 the trim valves T1, T2, T3 and T4 and the two switching valves X and Y are connected to the clutches C1, C2, C3 and C4 of the transmission 12 via an interposed network of supply lines 20 for moving hydraulic fluid. Oil, etc. through the tax system 10 and the gearbox 12 in fluid communication to control the clutches C1, C2, C3 and C4. The supply lines 20 are with the different connections 16 connected to the fluid communication with the valve body 14 manufacture.

In addition, the control system 10 a plurality of solenoids S1, S2, S3, S4, S5 and S6 for controlling the trim valves T1, T2, T3 and T4 and the two switching valves X and Y include. The solenoids S1, S2, S3, S4, S5 and S6 are designed so that each solenoid, S1, S2, S3, S4, S5 and S6, specifically a respective trim valve, T1, T2, T3 and T4, or switching valve, X and Y, to adjust the trim valve, T1, T2, T3 and T4, or the switching valve, X and Y, between a raised position and a non-raised position to be in the respective trim valve, T1, T2, T3 and T4, or switching valve, X and Y, to regulate entering and exiting fluid and the clutches C1, C2, C3 and C4 in the housing 13 to control.

The fluid circulates through the supply lines 20 between the case 13 and the tax system. The fluid is from the transmission 12 through the supply lines 20 and from the supply lines 20 through the trim valves T1, T2, T3 and T4 and the switching valves X and Y back to the clutches C1, C2, C3 and C4 within the housing 13 directed. The fluid can by means of a pump 22 through the supply lines 20 , the trim valves T1, T2, T3 and T4, the shift valves X and Y, the transmission 12 etc. are moved. The pump 22 may be a gear pump, a booster pump, etc. During operation, as the fluid moves through the trim valves T1, T2, T3, and T4 and / or the shift valves X and Y, a small amount of the fluid may pass between the valve housing 14 and the valve element 18 escape. The total system line pressure may be increased to cause leakage through the trim valves T1, T2, T3 and T4 and the shift valves X and Y. From the connections 16 go several refill channels 24 consisting of the trim valves T1, T2, T3 and T4 and the switching valves X and Y in the valve housing 14 within the transmission 12 connect with each other. The refill channels 24 Generally speaking, each of the electric motors A and B can be upside down 15 of the housing 13 run. The refill channels 24 trap this fluid as it escapes from the trim valves T1, T2, T3 and T4 and / or the shift valves X and Y, the fluid at a generally low pressure in the refill channels 24 to the top 15 of the housing 13 of the transmission 12 flows. The escaped fluid is routed through the motors A and B in the housing 13 flows to cool the electric motors A and B. Gravity pushes the fluid from the top 15 of the housing 13 via the electric motors A and B down. The fluid that has been passed to flow over the electric motors A and B, is in the housing 13 collected, with the fluid may be up to the top 14 of the housing fills to clutch piston cavities 17 to fill, with the clutch piston cavities 17 are each arranged in the immediate vicinity of the clutches C1, C2, C3 and C4. That in the case 13 flowing fluid creates a back pressure. The dynamic pressure in the housing 13 urges the fluid up to the top 15 of the housing 13 towards the clutch piston cavities 17 and at low pressure from the clutch piston cavities 17 into clutches C1, C2, C3 and C4 to remove any air trapped in clutches C1, C2, C3 and C4.

To the case 13 To provide additional fluid may include at least one bypass passage 19 between the supply lines 20 and the refill channels 24 be arranged. The bypass passage ensures that even if sufficient leakage can not be achieved by the trim valves T1, T2, T3, and T4 and / or the switching valves X and Y, an adequate amount of fluid is still through the refill channels 24 to the top 15 of the housing 13 flows. The bypass passage 19 therefore limits the flow of fluid between the supply lines 20 and the refill channels 24 while allowing a sufficient amount of fluid to flow through it. The fluid is from the supply lines 20 through the bypass passage 19 to the refill channels 24 directed.

As described above, the leakage from the trim valves T1, T2, T3 and T4 and / or the switching valves X and Y out through the refill channels 24 passed to the electric motors A and B to stator windings 26 the electric motors A and B to cool. If through the operation of the transmission 12 the temperature in the control system 10 increases, the temperature of the electric motors A and B increases. As the temperature of the electric motors A and B increases, therefore, more fluid is required to achieve the desired cooling of the electric motors A and B. When the temperature in the control system 10 However, the leakage of the fluid also increases, resulting in more fluid to meet the demand for cooling the electric motors A and B. If for some reason not enough fluid to cool the stator windings 26 the electric motors A and B is available, the valve elements 18 inside the valve body 14 be adjusted so that to supplement the escaped fluid fluid directly into the refill channels 24 is directed.

The electric motors A and B are preferably near the top 15 of the housing 13 of the transmission 12 arranged. In order to 2 to enter allows the placement of the electric motors A and B near the top 15 of the transmission 12 spraying or flowing the fluid over the stator windings 26 The electric motors A and B. From there, gravity can cause the fluid in the housing 13 down into a transmission tub 28 or another similar device that is near a bottom of the gearbox 12 is located, flows to the control system 10 and the transmission 12 to be used again.

In 3 is one of the trim valves, T1, shown. One of the refill channels 24 connects the trim valve T1 and the corresponding clutch C1 with each other. The refill pressure in the refill channels 24 is high enough to prime or "refill" the clutch C1, ie, to draw off air that may be contained in the clutch C1 when the clutch C1 is in an unactuated condition. Even though 3 It will be noted that there is a similar arrangement between each of the trim valves T2, T3 and T4 to withdraw any air from the respective clutches C2, C3 and C4 only the refill configuration for evacuating air from the clutch C1 via the trim valve T1.

Claims (13)

Method for supplying fluid to a housing ( 13 ) of a hybrid transmission ( 12 ), the method comprising the steps of: raising a total system line pressure to prevent fluid leakage or leakage of a control system ( 10 ) to bring about; Passing the escaped fluid through at least one refill channel ( 24 ) to the housing ( 13 ); and directing the escaped fluid through at least one electric motor (A, B) within the housing ( 13 ) to cool the at least one electric motor (A, B); Collecting the fluid conducted via the at least one electric motor (A, B) to 13 ) to create a dynamic pressure. The method of claim 1, wherein the collected fluid by the back pressure in the housing ( 13 ) in at least one clutch piston cavity ( 17 ) in the housing ( 13 ) is urged. The method of claim 2, wherein the collected fluid is removed from the at least one clutch piston cavity by the back pressure. 17 ) is forced into a respective clutch (C1, ..., C4) to extract air from the respective clutch (C1, ..., C4). The method of claim 1, wherein collecting the fluid further comprises collecting the fluid passing over the at least one electric motor (A, B) in a tub (14). 28 ) to a back pressure in the housing ( 13 ) is defined. The method of claim 1, further comprising: Passing the fluid from the transmission ( 12 ) by at least one supply line ( 20 ) to a valve (T1, T2, T3, T4, X, Y) and therethrough. Method according to claim 5, wherein the fluid is pumped by means of a pump ( 22 ) of the transmission ( 12 ) through the at least one supply line ( 20 ). Method according to claim 5, wherein the control system ( 10 ) is the valve (T1, T2, T3, T4, X, Y) to which the fluid is delivered. The method of claim 7, further comprising passing the fluid from the at least one valve (T1, T2, T3, T4, X, Y) through the at least one refill channel (12). 24 ). Method according to claim 1, wherein the control system ( 10 ) is a trim valve (T1, T2, T3, T4) and / or a switching valve (X, Y). The method of claim 1, further comprising directing the fluid from the at least one supply line ( 20 ) through a bypass passage ( 19 ) to the at least one refill channel ( 24 ). Tax system ( 10 ) for supplying a fluid to a hybrid transmission ( 12 ), whereby the tax system ( 10 ) comprises: at least one valve (T1, T2, T3, T4, X, Y) adapted to control the flow of fluid to the hybrid transmission ( 12 ) to regulate; at least one supply line ( 20 ) which is operatively connected to the at least one valve (T1, T2, T3, T4, X, Y) and is configured to remove the fluid between the hybrid transmission ( 12 ) and the valve (T1, T2, T3, T4, X, Y); at least one refill channel ( 24 ) which is operatively connected to the at least one valve (T1, T2, T3, T4, X, Y) and is adapted to the hybrid transmission ( 12 ) to supply a leaked fluid from the at least one valve (T1, T2, T3, T4, X, Y); and a bypass passage ( 19 ), the at least one supply line ( 20 ) and the at least one refill channel ( 24 ) is functionally connected and configured to the hybrid transmission ( 12 ) by the at least one refill channel ( 24 ) to supply additional fluid. A control system according to claim 11, wherein the at least one valve (T1, T2, T3, T4, X, Y) is a trim valve (T1, T2, T3, T4) and / or a switching valve (X, Y). A control system according to claim 11, further comprising a pump ( 22 ) connected to the at least one supply line ( 20 ) is functionally connected and serves the fluid from the hybrid transmission ( 12 ) through the at least one supply line ( 20 ) to transport.

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